scholarly journals GlnR Negatively Regulates Glutamate-Dependent Acid Resistance in Lactobacillus brevis

2020 ◽  
Vol 86 (7) ◽  
Author(s):  
Luchan Gong ◽  
Cong Ren ◽  
Yan Xu
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Glutamate Decarboxylase ◽  
Wild Type Strain ◽  
Acid Resistance ◽  
Lactobacillus Brevis ◽  
Deletion Strain ◽  
Content Type ◽  
Gaba Production ◽  
Encoding Gene

ABSTRACT Lactic acid bacteria often encounter a variety of multiple stresses in their natural and industrial fermentation environments. The glutamate decarboxylase (GAD) system is one of the most important acid resistance systems in lactic acid bacteria. In this study, we demonstrated that GlnR, a nitrogen regulator in Gram-positive bacteria, directly modulated γ-aminobutyric acid (GABA) conversion from glutamate and was involved in glutamate-dependent acid resistance in Lactobacillus brevis. The glnR deletion strain (ΔglnR mutant) achieved a titer of 284.7 g/liter GABA, which is 9.8-fold higher than that of the wild-type strain. The cell survival of the glnR deletion strain was significantly higher than that of the wild-type strain under the condition of acid challenge and was positively correlated with initial glutamate concentration and GABA production. Quantitative reverse transcription-PCR assays demonstrated that GlnR inhibited the transcription of the glutamate decarboxylase-encoding gene (gadB), glutamate/GABA antiporter-encoding gene (gadC), glutamine synthetase-encoding gene (glnA), and specific transcriptional regulator-encoding gene (gadR) involved in gadCB operon regulation. Moreover, GABA production and glutamate-dependent acid resistance were absolutely abolished in the gadR glnR deletion strain. Electrophoretic mobility shift and DNase I footprinting assays revealed that GlnR directly bound to the 5′-untranslated regions of the gadR gene and gadCB operon, thus inhibiting their transcription. These results revealed a novel regulatory mechanism of GlnR on glutamate-dependent acid resistance in Lactobacillus. IMPORTANCE Free-living lactic acid bacteria often encounter acid stresses because of their organic acid-producing features. Several acid resistance mechanisms, such as the glutamate decarboxylase system, F1Fo-ATPase proton pump, and alkali production, are usually employed to relieve growth inhibition caused by acids. The glutamate decarboxylase system is vital for GAD-containing lactic acid bacteria to protect cells from DNA damage, enzyme inactivation, and product yield loss in acidic habitats. In this study, we found that a MerR-type regulator, GlnR, was involved in glutamate-dependent acid resistance by directly regulating the transcription of the gadR gene and gadCB operon, resulting in an inhibition of GABA conversion from glutamate in L. brevis. This study represents a novel mechanism for GlnR's regulation of glutamate-dependent acid resistance and also provides a simple and novel strategy to engineer Lactobacillus strains to elevate their acid resistance as well as GABA conversion from glutamate.

scholarly journals Arabinoxylan Oligosaccharide Hydrolysis by Family 43 and 51 Glycosidases from Lactobacillus brevis DSM 20054

2013 ◽  
Vol 79 (21) ◽  
pp. 6747-6754 ◽  
Author(s):  
Herbert Michlmayr ◽  
Johannes Hell ◽  
Cindy Lorenz ◽  
Stefan Böhmdorfer ◽  
Thomas Rosenau ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Functional Food ◽  
Specific Activity ◽  
High Specific Activity ◽  
Lactobacillus Brevis ◽  
Glycoside Hydrolases ◽  
Content Type ◽  
Food And Feed ◽  
Oligosaccharide Hydrolysis

ABSTRACTDue to their potential prebiotic properties, arabinoxylan-derived oligosaccharides [(A)XOS] are of great interest as functional food and feed ingredients. While the (A)XOS metabolism ofBifidobacteriaceaehas been extensively studied, information regarding lactic acid bacteria (LAB) is still limited in this context. The aim of the present study was to fill this important gap by characterizing candidate (A)XOS hydrolyzing glycoside hydrolases (GHs) identified in the genome ofLactobacillus brevisDSM 20054. Two putative GH family 43 xylosidases (XynB1 and XynB2) and a GH family 43 arabinofuranosidase (Abf3) were heterologously expressed and characterized. While the function of XynB1 remains unclear, XynB2 could efficiently hydrolyze xylooligosaccharides. Abf3 displayed high specific activity for arabinobiose but could not release arabinose from an (A)XOS preparation. However, two previously reported GH 51 arabinofuranosidases fromLb. breviswere able to specifically remove α-1,3-linked arabinofuranosyl residues from arabino-xylooligosaccharides (AXHm3 specificity). These results imply thatLb. brevisis at least genetically equipped with functional enzymes in order to hydrolyze the depolymerization products of (arabino)xylans and arabinans. The distribution of related genes inLactobacillalesgenomes indicates that GH 43 and, especially, GH 51 glycosidase genes are rare among LAB and mainly occur in obligately heterofermentativeLactobacillusspp.,Pediococcusspp., members of theLeuconostoc/Weissellabranch, andEnterococcusspp. Apart from the prebiotic viewpoint, this information also adds new perspectives on the carbohydrate (i.e., pentose-oligomer) metabolism of LAB species involved in the fermentation of hemicellulose-containing substrates.

scholarly journals Role of Plasmids in Lactobacillus brevis BSO 464 Hop Tolerance and Beer Spoilage

2014 ◽  
Vol 81 (4) ◽  
pp. 1234-1241 ◽  
Author(s):  
Jordyn Bergsveinson ◽  
Nina Baecker ◽  
Vanessa Pittet ◽  
Barry Ziola
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Lactobacillus Brevis ◽  
The Other ◽  
Plasmid Curing ◽  
Content Type ◽  
Dramatic Effect ◽  
Plasmid Loss ◽  
Beer Spoilage

ABSTRACTSpecific isolates of lactic acid bacteria (LAB) can grow in the harsh beer environment, thus posing a threat to brew quality and the economic success of breweries worldwide. Plasmid-localized genes, such ashorA,horC, andhitA, have been suggested to confer hop tolerance, a trait required for LAB survival in beer. The presence and expression of these genes among LAB, however, do not universally correlate with the ability to grow in beer. Genome sequencing of the virulent beer spoilage organismLactobacillus brevisBSO 464 revealed the presence of eight plasmids, with plasmids 1, 2, and 3 containinghorA,horC, andhitA, respectively. To investigate the roles that these and the other five plasmids play inL. brevisBSO 464 growth in beer, plasmid curing with novobiocin was used to derive 10 plasmid variants. Multiplex PCRs were utilized to determine the presence or absence of each plasmid, and how plasmid loss affected hop tolerance and growth in degassed (noncarbonated) beer was assessed. Loss of three of the eight plasmids was found to affect hop tolerance and growth in beer. Loss of plasmid 2 (horCand 28 other genes) had the most dramatic effect, with loss of plasmid 4 (120 genes) and plasmid 8 (47 genes) having significant, but smaller, impacts. These results support the contention that genes on mobile genetic elements are essential for bacterial growth in beer and that beer spoilage ability is not dependent solely on the three previously described hop tolerance genes or on the chromosome of a beer spoilage LAB isolate.

scholarly journals Production of γ-aminobutyric acid (GABA) by lactic acid bacteria strains isolated from traditional, starter-free dairy products made of raw milk

2019 ◽  
Vol 10 (5) ◽  
pp. 579-587 ◽  
Author(s):  
J.A. Valenzuela ◽  
A.B. Flórez ◽  
L. Vázquez ◽  
O.M. Vasek ◽  
B. Mayo
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Dairy Products ◽  
Culture Media ◽  
Monosodium Glutamate ◽  
Lactobacillus Brevis ◽  
Raw Milk ◽  
Starter Cultures ◽  
Aminobutyric Acid ◽  
Gaba Production

γ-Aminobutyric acid (GABA), an amino acid not used in protein synthesis, intervenes in several physiological functions and has both diuretic and calming effects in humans. Lactic acid bacteria (LAB) strains that produce GABA could be exploited for the manufacture of health-promoting GABA-enriched dairy products. In this study, 262 LAB strains isolated from traditional dairy products made from raw milk without starter cultures were screened for GABA production in culture media supplemented with 1% monosodium glutamate (MSG) using an enzymatic (GABase) method. About half of the strains (123) were found to be GABA producers. Of these, 24, among which were 16 Lactococcus lactis subsp. lactis and three Streptococcus thermophilus strains, produced >1 mM of GABA (range 1.01-2.81 mM) and were selected for further characterisation. GABA production was confirmed in most strains by culturing in 5 mM MSG followed by HPLC quantification. A majority of the strains were confirmed to be GABA producers by this method, although lower production levels were recorded. Using species-specific primers, the gene encoding glutamate decarboxylase (GAD) was PCR-amplified in all but one of the GABA producers analysed. Amplicons sequences were compared to one another and to those held in databases. Except for one Lactobacillus brevis strain, none of the 24 GABA producers investigated produced toxic biogenic amines, such as tyramine, histamine or cadaverine. They were therefore considered safe. Either alone, in mixtures, or in combination with industrial starter or adjunct cultures, these strains might be useful in the development of health-oriented dairy products.

scholarly journals Effect of Lineage-Specific Metabolic Traits of Lactobacillus reuteri on Sourdough Microbial Ecology

2014 ◽  
Vol 80 (18) ◽  
pp. 5782-5789 ◽  
Author(s):  
Xiaoxi B. Lin ◽  
Michael G. Gänzle
Keyword(s):  
Glutamate Decarboxylase ◽  
Type Strain ◽  
Wild Type Strain ◽  
Lactobacillus Reuteri ◽  
Acid Resistance ◽  
Glycerol Metabolism ◽  
Wild Type ◽  
Content Type ◽  
Glycerol Dehydratase ◽  
Metabolic Traits

ABSTRACTThis study determined the effects of specific metabolic traits ofLactobacillus reuterion its competitiveness in sourdoughs. The competitiveness of lactobacilli in sourdough generally depends on their growth rate; acid resistance additionally contributes to competitiveness in sourdoughs with long fermentation times. Glycerol metabolism via glycerol dehydratase (gupCDE) accelerates growth by the regeneration of reduced cofactors; glutamate metabolism via glutamate decarboxylase (gadB) increases acid resistance by generating a proton motive force. Glycerol and glutamate metabolisms are lineage-specific traits inL. reuteri; therefore, this study employed glycerol dehydratase-positive sourdough isolates of human-adaptedL. reuterilineage I, glutamate decarboxylase-positive strains of rodent-adaptedL. reuterilineage II, as well as mutants with deletions ingadBorgupCDE. The competitivenesses of the strains were quantified by inoculation of wheat and sorghum sourdoughs with defined strains, followed by propagation of doughs with a 10% inoculum and 12-h or 72-h fermentation cycles. Lineage IL. reuteristrains dominated sourdoughs propagated with 12-h fermentation cycles; lineage IIL. reuteristrains dominated sourdoughs propagated with 72-h fermentation cycles.L. reuteri100-23ΔgadBwas outcompeted by its wild-type strain in sourdoughs fermented with 72-h fermentation cycles;L. reuteriFUA3400ΔgupCDEwas outcompeted by its wild-type strain in sourdoughs fermented with both 12-h and 72-h fermentation cycles. Competition experiments with isogenic pairs of strains resulted in a constant rate of strain displacement of the less competitive mutant strain. In conclusion, lineage-specific traits ofL. reuteridetermine the competitiveness of this species in sourdough fermentations.

scholarly journals Assessment of Probiotic Properties of Lactic Acid Bacteria from Traditional Sourdoughs for Bread-Making in Turkey against Some Gut Conditions

2019 ◽  
Vol 6 (2) ◽  
Author(s):  
Murat Doğan ◽  
İsmail Hakkı Tekiner
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Acid Resistance ◽  
Lactobacillus Brevis ◽  
Property Testing ◽  
Probiotic Properties ◽  
Bread Making ◽  
Lactobacillus Pentosus ◽  
Microbiological Methods ◽  
Bile Resistance

This study aims to assess the probiotic properties of Lactic Acid Bacteria isolated from the traditional sourdoughs used for bread making in Turkey against some gut conditions. A total number of 29 samples from twelve provinces of Turkey were collected, and screened for the presence of lactic acid bacteria using microbiological methods. The microbiological screening yielded 148 presumptive isolates. Of them, 62.8% were characterized as lactic acid strains by VITEK® MS. Following that, the characterized isolates were subjected to probiotic property testing, including gastric acid resistance, bile resistance and hydrophobic ability. The results showed that 44.1% exceeded gastric pH resistance, 33.3% survived under gastrointestinal system bile salt conditions, and 10.8% exhibited high hydrophobicity ability. In conclusion, our study revealed that only 4.3% (1 Enterococcus faecium, 1 Lactobacillus brevis, 1 Lactobacillus pentosus, and 1 Lactobacillus plantarum) out of 93 lactic acid bacteria isolated from the traditional sourdoughs could meet all probiotic requirements against some gut conditions. 

scholarly journals Core Fluxome and Metafluxome of Lactic Acid Bacteria under Simulated Cocoa Pulp Fermentation Conditions

2013 ◽  
Vol 79 (18) ◽  
pp. 5670-5681 ◽  
Author(s):  
Philipp Adler ◽  
Christoph Josef Bolten ◽  
Katrin Dohnt ◽  
Carl Erik Hansen ◽  
Christoph Wittmann
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Starter Cultures ◽  
Superior Performance ◽  
Gas Chromatography Mass Spectrometry ◽  
Glycolytic Flux ◽  
Content Type ◽  
Phosphoketolase Pathway ◽  
Labeling Approach ◽  
Cocoa Fermentation

ABSTRACTIn the present work, simulated cocoa fermentation was investigated at the level of metabolic pathway fluxes (fluxome) of lactic acid bacteria (LAB), which are typically found in the microbial consortium known to convert nutrients from the cocoa pulp into organic acids. A comprehensive13C labeling approach allowed to quantify carbon fluxes during simulated cocoa fermentation by (i) parallel13C studies with [13C6]glucose, [1,2-13C2]glucose, and [13C6]fructose, respectively, (ii) gas chromatography-mass spectrometry (GC/MS) analysis of secreted acetate and lactate, (iii) stoichiometric profiling, and (iv) isotopomer modeling for flux calculation. The study of several strains ofL. fermentumandL. plantarumrevealed major differences in their fluxes. TheL. fermentumstrains channeled only a small amount (4 to 6%) of fructose into central metabolism, i.e., the phosphoketolase pathway, whereas onlyL. fermentumNCC 575 used fructose to form mannitol. In contrast,L. plantarumstrains exhibited a high glycolytic flux. All strains differed in acetate flux, which originated from fractions of citrate (25 to 80%) and corresponding amounts of glucose and fructose. Subsequent, metafluxome studies with consortia of differentL. fermentumandL. plantarumstrains indicated a dominant (96%) contribution ofL. fermentumNCC 575 to the overall flux in the microbial community, a scenario that was not observed for the other strains. This highlights the idea that individual LAB strains vary in their metabolic contribution to the overall fermentation process and opens up new routes toward streamlined starter cultures.L. fermentumNCC 575 might be one candidate due to its superior performance in flux activity.

Cell-free supernatants produced by lactic acid bacteria reduce Salmonella population in vitro

Microbiology ◽  
2021 ◽  
Vol 167 (11) ◽  
Author(s):  
Alberto Gonçalves Evangelista ◽  
Jessica Audrey Feijó Corrêa ◽  
João Vitor Garcia dos Santos ◽  
Eduardo Henrique Custódio Matté ◽  
Mônica Moura Milek ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Lactic Acid ◽  
Antimicrobial Resistance ◽  
Lactic Acid Bacteria ◽  
Type Species ◽  
Feed Additives ◽  
Poultry Feed ◽  
Content Type ◽  
Link Type

The genus Salmonella is closely associated with foodborne outbreaks and animal diseases, and reports of antimicrobial resistance in Salmonella species are frequent. Several alternatives have been developed to control this pathogen, such as cell-free supernatants (CFS). Our objective here was to evaluate the use of lactic acid bacteria (LAB) CFS against Salmonella in vitro. Seventeen strains of LAB were used to produce CFS, and their antimicrobial activity was screened towards six strains of Salmonella . In addition, CFS were also pH-neutralized and/or boiled. Those with the best results were lyophilized. MICs of lyophilized CFS were 11.25–22.5 g l–1. Freeze-dried CFS were also used to supplement swine and poultry feed (11.25 g kg–1) and in vitro simulated digestion of both species was performed, with Salmonella contamination of 5×106 and 2×105 c.f.u. g−1 of swine and poultry feed, respectively. In the antimicrobial screening, all acidic CFS were able to inhibit the growth of Salmonella . After pH neutralization, Lactobacillus acidophilus Llorente, Limosilactobacillus fermentum CCT 1629, Lactiplantibacillus plantarum PUCPR44, Limosilactobacillus reuteri BioGaia, Lacticaseibacillus rhamnosus ATCC 7469 and Pediococcus pentosaceus UM116 CFS were the only strains that partially maintained their antimicrobial activity and, therefore, were chosen for lyophilization. In the simulated swine digestion, Salmonella counts were reduced ≥1.78 log c.f.u. g–1 in the digesta containing either of the CFS. In the chicken simulation, a significant reduction was obtained with all CFS used (average reduction of 0.59±0.01 log c.f.u. ml–1). In general, the lyophilized CFS of L. fermentum CCT 1629, L. rhamnosus ATCC 7469 and L. acidophilus Llorente presented better antimicrobial activity. In conclusion, CFS show potential as feed additives to control Salmonella in animal production and may be an alternative to the use of antibiotics, minimizing problems related to antimicrobial resistance.

scholarly journals Complete Genome Sequence of Lactobacillus reuteri Byun-re-01, Isolated from Mouse Small Intestine

2018 ◽  
Vol 7 (17) ◽  
Author(s):  
Dongjun Kim ◽  
Mun-ju Cho ◽  
Seungchan Cho ◽  
Yongjun Lee ◽  
Sung June Byun ◽  
...  
Keyword(s):  
Small Intestine ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Lactobacillus Reuteri ◽  
Probiotic Bacteria ◽  
Content Type ◽  
Mouse Small Intestine

Lactic acid bacteria (LAB) are generally recognized as safe (GRAS) and serve as probiotic bacteria when consumed in adequate amounts. Here, we report the complete genome sequence of Lactobacillus reuteri Byun-re-01, isolated from mouse small intestine.

GROWTH RATES AND FERMENTATION PATTERNS OF LACTIC ACID BACTERIA ASSOCIATED WITH THE SAUERKRAUT FERMENTATION1

1971 ◽  
Vol 34 (11) ◽  
pp. 521-525 ◽  
Author(s):  
J. R. Stamer ◽  
B. O. Stoyla ◽  
B. A. Dunckel
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Growth Rates ◽  
Leuconostoc Mesenteroides ◽  
Lactobacillus Brevis ◽  
Sensitive Species ◽  
Ph Values ◽  
Generation Times ◽  
Effects Of Ph ◽  
Early Phases

The effects of pH values and NaCl concentrations on the growth rates of five species of lactic acid bacteria commonly associated with the sauerkraut fermentation were determined in filter-sterilized cabbage juice. Growth rates of all cultures, with the exception of Pediococcus cerevisiae, were retarded by addition of salt, lower pH, or interaction of both pH and salt. Based upon lag and generation times, P. cerevisiae was the culture most tolerant to the pH and salt concentration employed, whereas Streptococcus faecalis was the most sensitive species. Of the heterofermentative cultures, Lactobacillus brevis was less subject to growth inhibition than Leuconostoc mesenteroides. Under conditions simulating those found during the initial phases of the sauerkraut fermentation (2.25% salt, pH 6.2), L. mesenteroides displayed the shortest lag and generation times of all cultures examined. This rapid growth rate coupled with a marked accelerated death rate may explain, in part, the reason this species is both the first to dominate and the first to die during the early phases of the sauerkraut fermentation. Although cabbage juice previously fermented by L. mesenteroides appears to inhibit growth of P. cerevisiae, it had no apparent inhibitory or stimulatory effects on the other cultures.

Influence of Lactobacillus brevis 15 and Lactobacillus plantarum 13 on blood glucose and body weight in rats after high-fructose diet

2015 ◽  
Vol 6 (4) ◽  
pp. 505-512 ◽  
Author(s):  
M. Yakovlieva ◽  
T. Tacheva ◽  
S. Mihaylova ◽  
R. Tropcheva ◽  
K. Trifonova ◽  
...  
Keyword(s):  
Body Weight ◽  
Lactic Acid ◽  
Blood Glucose ◽  
Lactic Acid Bacteria ◽  
Lactobacillus Plantarum ◽  
Lactobacillus Brevis ◽  
Control Group ◽  
Standard Diet ◽  
Glucose Levels ◽  
Blood Glucose Levels

In recent years, many authors have investigated the possible antidiabetic effect of lactic acid bacteria. Lactobacillus species constitute a major part of the lactic acid bacteria group and have been found to exhibit beneficial effects on the development of diabetes and its complications. In the current study, we investigated the effects of newly characterised Bulgarian Lactobacillus strains, Lactobacillus brevis 15 and Lactobacillus plantarum 13, on blood glucose levels and body weight of rats fed a fructose-enriched diet. An experiment was conducted over a period of 8 weeks with 24 2-month-old Wistar rats randomly assigned to receive a standard diet (Con, control group), fructose-enriched diet (Fr group), standard diet with probiotics given twice a week (Pro group), and fructose-enriched diet with probiotics given twice a week (Pro+Fr group). At the end of the experimental period, a statistically significant increase in body weight was observed in all experimental groups (P<0.0001). The highest rise was seen in the fructose group (Fr, 169±19 g), followed by the Pro+Fr group (153±15 g), Pro group (149±13 g), and Con group (141±5 g). Moreover, the final blood glucose levels had risen significantly in the groups receiving fructose either without (Fr; P<0.0001) or with lactobacilli (Pro+Fr; P=0.002), while the rise was insignificant in the group of rats given probiotic supplementation only (Pro, P=0.071) and inexistent in the Con group (P=0.999). The highest elevation of blood glucose levels was observed in the Fr group (3.18 mmol/l), followed by the Pro+Fr group (2.00 mmol/l) whereas the Pro group showed the lowest levels (0.60 mmol/l). The results of our study suggest that the newly characterised Bulgarian Lactobacillus strains, L. brevis 15 and L. plantarum 13, could be considered as possible probiotics and might be able to prevent some metabolic disturbances.

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